1. Field
This disclosure relates to a multi-functional cabin air filter utilizable in a limited space such as a vehicle.
2. Description of the Related Art
A vehicle has a general air filter with a dust collecting function, which is also called an air conditioner filter, and the air filter is inserted into an inlet of an air conditioner of the vehicle. However, in most cases, the air filter just has a dust collecting function, and it is not provided with a gaseous contaminant removing function or an antimicrobial function.
Recently, air conditioner filters having additional functions such as an antimicrobial or deodorizing function in addition to the dust collecting function have been released in the market. To remove gaseous air pollutants, an adsorbent such as activated carbon is used. In some products, a room-temperature catalyst filter is coupled to decompose and remove the adsorbed gaseous substances.
However, air pollutants contaminating the indoor of a vehicle include fine dust and nitrogen oxides emitted from a vehicle exhaust pipe to the road. Nitrogen oxides include nitrogen monoxide and nitrogen dioxide, and nitrogen monoxide occupies about 90% or more of the nitrogen oxides emitted from a vehicle. In the air, nitrogen monoxide is oxidized into nitrogen dioxide through atmospheric chemical reaction. Accordingly, in the vehicle indoor contaminated by high-concentration exhaust gas emitted from a vehicle, the concentration of nitrogen monoxide is higher than that of nitrogen dioxide. However, a general adsorbent such as activated carbon adsorbs a relatively small amount of nitrogen monoxide though its adsorbing performance for nitrogen dioxide is excellent. Thus, in order to efficiently remove nitrogen monoxide, another technique is required in addition to the adsorbent.
Also, in case a filter is provided with an antimicrobial function by applying a biodegradable antimicrobial agent such as chitosan to a dust collecting filter, the antimicrobial agent may be degraded with the lapse of use or storage time, thereby deteriorating the antimicrobial function. In addition, in case of an antimicrobial filter made by coating its surface with a liquid-phase inorganic antimicrobial agent such as silver, a large amount of antimicrobial agent is nonuniformly coated on the surface, which may result in inappropriate antimicrobial function or cause additional pressure drop across the filter.